Crown-tooth.



A. FERNALD.

CROWN TOOTH.

APPLICATION FILED MAY 3. m5.

Patented Dec. 14,1915.

I'IVVEIVTOR,

WITNESSES.

COLUMBIA PLANOQRAPH (10., WASHINGTON, mt.

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ADELBERT rnnnnLn, or BOSTON, MASSACHUSETTS.

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Specification of Letters Patent.

Patented Dec. ML, 1915.

Application filed May 3, 1915. Serial No. 25,48L.

To all whom it may concern:

Be it known that I, ADELBERT FERN'ALD, a.

citizen of the United States, residing at Boston, in the county of Suifolk, in the State of Massachusetts, have invented a certain new and useful Improvement in Crown- Teeth, of which the following is a specifiation, reference being had to the accompanying drawings.

The immediate object of this invention is.

to provide a specially strong, serviceable and sanitary means for crowning broken, decayed, or otherwise useless teeth in which the roots are still in a healthy and usable condition, thus making it possible to preserve the usefulness of such teeth for a long period of time.

In order to explain my invention clearly, I have provided the annexed drawings, in which Figure 1 is a vertical, sectional, view of a molar which has been prepared for crown ing by my improved means, the said tooth having been faced off on its exposed surface and also having been drilled and undercut to receive an anchor which serves as an important element of my crowning means. Fig. 2 is a similar view showing the crown mounted upon the prepared root, and Fig. 3 is a like view showing the thin metallic plate, between the root and crown, formed as a double cup or cap as I will describe more particularly later. In Fig. 4 I have illustrated the said plate formed as a single cap. Fig. 5 is a top view of the molar of Fig. 1. Figs. 6 and 7 are, respectively perspective and side views of the anchor which I have referred to above. Fig. 8 is a perspective view of the double cap shown in Fig. 3, the rim of said cap being partly,

broken away.

Referring to these drawings the letter (4 indicates the root of a back tooth or molar and b a crown mounted upon said root and secured thereto by my improved means.

As here illustrated the root is drilled approximately centrally and the base of the small opening thus made is enlarged to form a chamber 0 which is adapted to receive the enlarged end portion d of a pivot wire cl, the relatively smaller central opening above described being elongated in cross section, or otherwise formed, so that the enlargement cl may be entered into the chamber 0 and so positioned that the said enlargement will be locked in the chamber so long as the pivot wire a? is kept in' parallel relation to the axial center of the tooth; the enlargement 03 operating then as an anchor to prevent the removal of the pivot wire and the separation of the crown from the root, as I will describe more fully later.

The crown b is also drilled approximately centrally to receive the extended upper end portion of the pivotwire.

Having provided the several described parts, to wit: the root, the crown and the metallrc connection for the root and crown, and having properly fitted the said parts to each other, the anchor enlargement cl is first entered in the cavity 0 and is firmly cemented therein preferably by means of amalgam.

A d1sk e, centrally perforated, preferably of thin sheet gold, is first slipped onto the pivot wire (Z, a nut q is screwed down on said pivot wire until the disk 6 is firmly seated on the fiat surface of the root (1 and the crown b is finally slipped downward on the pivot wire (Z and securely cemented in its operative position.

The interposed disk 6 may be simply fiat,

as in Fig. 2, or it may be cupped as seen in Fig. 4, to provide a downwardly extending protection rim which encircles the upper portion of the root, or the disk may be formed as a double cup as in Figs. 3 and 8 in order to provide a specially strong support and connection between the root and crown, and also to prevent particles of food, and other objectionable matter, from entering between the root and crown. When thus assembled and secured together, the crown and root become, in effect, a single solid structure capable of performing all of the functions of a healthy natural tooth.

In the process of crowning a front tooth root, I employ the pivot wire (Z, the thin metal plate 6 and the nut precisely as already described in connection with the crowning of a molar.

I find by actual use and demonstration that my described connection between the crown and root provides a particularly strong and serviceable means for crowning teeth and that it is not objectionable expensive.

Having thus described my invention I claim as new and wish to secure by Letters Patent The improvement in means for crowning teeth, which consists of a septum or plate applied intermediate of the tooth-root and the crown, said septum having a central opening therethrough, a centering pivot, having an anchoring disk-llke terminal at its lower end let into an undercut socket in the upper end of the tooth-root, said centering pivot passing through the central opening of said septum or plate and having threaded thereon a nut clamping the an" Copies of this patent may be obtained for choring terminal of said'centering pivot together With said septum or plate in position in said socket and upon said tooth-root,

respectively, said septum or plate having its five cents each, by addressing the Commissioner of Patents, Washington,'D. .0. 

